The preparation of carbon-carbon coupled condensation products of alkylphenols is well-known in the art. The preparation generally uses oxygen and a catalyst (e.g. ferric chloride).
The procedure can be illustrated as follows: ##STR1##
R is usually either hydrogen or an alkyl group in the above.
Biphenols are useful as antioxidants, stabilizers and as intermediates in the synthesis of various polymers, particularly polyesters. Diphenoquinones are useful as antioxidants.
I have discovered an improved method of preparing carbon-carbon coupled condensation products of certain alkylphenols which uses palladium acetate as the catalyst.
The process possesses several advantages. First, it produces the desired product in high selectivity. Second, greater ease in product isolation is possible since only a small (i.e. catalytic) amount of palladium acetate is required.